-LRB- CNN -RRB- -- Christina Cimino was logging onto Twitter on Thursday morning when something happened that she found deeply unsettling .

iReporter David Seaman says Twitter needs a competitor so users do n't panic when it goes down .

`` I got some weird error message , and I 'm like , ` What 's going on !? '' the 24-year-old said .

That error message was the scourge of online social networkers worldwide on Thursday as cyber-attacks shut down Twitter and caused sustained glitches in other social-media sites like Facebook and the blogging site LiveJournal .

Twitter co-founder Biz Stone wrote the sites were the victims of what `` appears to be a single , massively coordinated attack . '' And a pro-Georgian blogger , whose accounts on Facebook and Twitter reportedly were the targets of the denial-of-service attack , told CNN the online strike was timed to coincide with the one-year anniversary of the Russia-Georgia conflict .

What may prove more lasting about the day social networking suffered its first major blackout is the degree to which people cared . Near-panic erupted in some corners of the Internet as people lost cherished links to their online friends , family members and news feeds . Watch CNN iReporters talk about the attack

Part of the panic relates to the sheer popularity of the sites .

Twitter saw a more than 1,300 percent jump in unique visitors between February 2008 and February 2009 , according to Nielsen NetView . The site , which lets users post messages of 140 characters or less , had more than 44 million worldwide users in June , according to comScore . More than 120 million users log onto Facebook at least one time each day , the site says .

To be sure , not all Facebook and Twitter users freaked out because of the attacks . Some people even reveled in the mayhem . Blog : Could the attacks be our fault ?

But for people like Cimino , who said she `` felt naked '' without access to Twitter , the attacks were a serious reality check -- a chance to evaluate just how dependent they 'd become .

`` You know how you pat your pockets for your cell phone and your keys ? Well it 's that same kind of phantom -LSB- limb -RSB- with Twitter , '' she said . `` It 's like , ' I ca n't update ! I ca n't update ! ' It 's just one of those bugs that gets in you . ''

She added : `` I was pretty upset , actually . It feels like a lifeline for me ... Pretty much everyone knows almost every detail of my life by what I 'm doing on Twitter . ''

It 's not worth analyzing whether these online connections are good or bad because the reality is that Twitter and Facebook are now an important part of our lives , said Marc Cooper , a journalism professor at the University of Southern California 's Annenberg School for Communication .

`` For many people , and not just young people , the Web is not just media , it 's actually a place where they conduct their lives or a portion of their lives , '' he said .

`` So the panic -LSB- Thursday -RSB- morning is only reflective of that . This is not just a hobby or an amusement or another accoutrement , it 's actually deeply woven into their lives and is integral to their social interaction . So when it 's cut off , it 's a problem . ''

Others saw Twitter 's existence as the problem and relished the chance to make fun of a Web site that has become so omnipresent in news cycles .

`` Horrors !!! People will have to communicate face to face ! '' one user commented on CNN 's SciTech blog .

Another commenter said , `` Turn off your computers and read a book or get outside and discover there is more to life than cyberspace . The Internet has become nothing more than the new cocaine . ''

Now that Twitter is back online , the No. 1 conversation thread on the site is called `` whentwitterwasdown , '' where users discuss what they did without their real-time Twitter updates .

Some people are mocking the blackout . A user named PaulWilks , for instance , wrote , `` I took up juggling . ''

Others seem concerned . `` I did absolutely nothing . It 's like my heart was gone , '' wrote a user named HarajukuxBarbie . `` I felt so empty inside , '' wrote another Twitter user called freinhar .

Some business people on Thursday realized just how much they depend on Facebook and Twitter to do their work .

Adam Ostrow , editor-in-chief at Mashable , a blog that covers social media , said the outage made it difficult for his organization to cover the news and to promote its stories .

`` For someone like myself who spends all day on Twitter , it 's incredibly frustrating , '' he told CNN.com Live .

Justin Stauffer , a 31-year-old who works in Web strategy at a marketing company near Philadelphia , Pennsylvania , said Thursday 's attack made him realize just how dependent on Twitter he had become .

`` When something that 's so central to how you do your business or how you gather information goes down , yeah , you get a little jittery -- like , when 's it going to be back , '' he said .

`` I did n't break out in hives or anything like that , '' he said , jokingly .

David Seaman , an iReporter in New York , said he thinks Twitter needs a competitor so users will have an alternative if the site is down . Watch Seaman 's talk about the issue on CNN 's iReport

And Amy Gahran , who writes about social media on a blog called Contentious , said all technologies can break down , so people need to make contingency plans .

`` Hell , when you get down to it , you can lose your voice or break your writing hand or have a stroke and be unable to communicate . We are fundamentally social creatures , and when we lack our usual communication channels it 's scary , '' she writes .

`` Do n't panic . Have a backup plan , and be prepared . ''

Cooper , the USC professor , said the fuss surrounding Thursday 's attack is a sign that instant , online communication is here to stay .

Fighting the trend would be like trying to stop the ocean 's tides , he said , but it 's unclear where the technology will take our society .

`` The bottom line is that we do n't know . All of this is too new , '' he said . `` It 's like sitting around in the year 1500 and trying to figure out where the printing press was going to take us . ''

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Some Twitter and Facebook users panicked as the sites went down Thursday

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Several online social networks were the victims of cyber-attacks

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One Twitter user says she felt `` naked '' without her micro-blog

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Another says he felt `` jittery '' during the time Twitter was down